Weight loss and maintenance continue to be problematic for individuals who are overweight or obese. State-of-the-art treatment is delivered face-to-face between care providers and small groups of participants and this is time consuming, expensive, and presents numerous barriers to the participant such as travel, conflict with work and home, need for child care, loss of anonymity, and others as well as the care provider such as office space, meeting rooms, inventory, and so on. A pilot study of a phone based delivery system versus a traditional clinic has been completed with no difference in weight loss. The phone approach may eliminate many of the barriers of a traditional clinic by substituting conference calls for clinics and by delivering weight loss materials and products directly to the participant. In this fashion, the care provider and participants can reside in any location and receive the same information by conference phone call as that provided by clinic, and receive educational materials, weight management products, and so on, by air or ground transportation. This proposed investigation is a randomized, equivalency trial to test the effectiveness of a phone based weight management program compared to a traditional face-to-face clinic program for weight loss and weight maintenance. It is expected that at 6 months participants in the phone and clinic groups will show equivalent weight loss and that weight loss will be at least 10 percent lower than baseline. During weight maintenance some weight gain may occur. However, we expect both phone and clinic groups to gain a similar amount of weight and that weight for both groups at 18 months will be significantly less than baseline weights. A formal cost analysis will be used to determine differences between phone and clinic approaches and extensive process analysis will be used to collect both qualitative and quantitative data to assess how well the programs were implemented as originally designed, challenges and barriers to effective implementation, initial and continual use of program specified activities, quality assurance measures, and so on. Relevance: If successful, the phone approach may eliminate many of the barriers inherent to the traditional face-to-face clinic, may be less expensive, and would potentially open weight management to any individual with access to a phone. We believe the likelihood of translation of this research to the public sector would seem reasonable and promising.